The present invention relates to an adhesive system for forming reversible adhesive bonds, comprising at least one polymeric adhesive component based on polyurethanes and/or polyureas and/or epoxy resins and at least one additional component. The present invention further relates to a process for the reversible bonding of articles and controlled parting of the adhesive bond obtained.
In a very wide variety of technical fields, articles are nowadays bonded to one another. In particular welded connections which have been customary to date are being replaced by adhesive bonds. High-strength adhesive bonds with resistance properties are required for this purpose. This is especially the case in connection with the production of motor vehicles. A disadvantage with this method of construction is that, for a refinish or for recycling, the individual bonded components of the motor vehicles are difficult to separate, their separation being time-consuming and requiring force: for example, by means of a hammer and chisel, or by sawing or flame cutting.
Adhesive systems of this generic type are known, for example, from U.S. Pat. No. 4,599,273. This document relates to surface-active substances whose surface-active effect is blocked by additional components in the form of photolabile protective groups. By exposure to radiation, the protective groups are removed and the surface-active effect is re-established. Surface-active substances of this kind may also comprise coatings which may be applied reversibly. However, they cannot be used to realize high-strength adhesive bonds.
DE 92 16 278 U1 discloses pressure-sensitive adhesives with which components of motor vehicles can be reversibly bonded to one another. These adhesives too cannot be used to realize high-strength adhesive bonds.
It is therefore the object of the present invention to provide adhesive systems of the type specified above with which high-strength adhesive bonds can be produced and which in a simple manner permit controlled mechanical separation of the articles bonded to one another.
This object is achieved by the at least one additional component comprising at least one functional group which can be activated by introduction of energy, in such a way that a chemical reaction with the adhesive component takes place, involving at least partial breakdown of the adhesive component.
The process of the invention is distinguished by the following steps:
preparation of an adhesive bond using an adhesive system of the invention,
deactivation of the adhesive bond by introduction of energy,
separation of the articles from one another.